1. Field of the Invention
The present invention relates a synthetic resin joint for connecting a plurality of resin-coated steel pipes, each of which has a resin coating on a peripheral surface of a thin wall steel pipe and formed with at least one pair of fitting ribs for holding an edge of a panel form or a net form partitioning body, by a bond, in order to form small scale pipe structures such as a recovery platform, a jumble kart or so forth.
2. Description of the Related Art
Conventionally, as a joint of the type, to which the present invention concerned, it has been known a synthetic resin joint 103 formed by intersectingly connecting a plurality of cylindrical tubes 101 and 102 via an adhesive or a bond, to which resin-coated metal beams formed by coating surfaces (outer peripheral surfaces) of thin wall steel pipes by a synthetic resin material, as shown in FIG. 37.
It should be noted that there are a large number of kinds of joints depending upon form (blind, through or so forth) to be connected, and lengths, number, relative positions, orientations and the like of respective cylindrical tubes.
However, when a plurality of resin-coated metal beams 108, each of which is formed with at least one pair of fitting ribs 107 over the entire length thereof on a coat resin 105 coating a surface (outer peripheral surface) of a thin wall steel pipe 104 in order to hold an edge of a panel form or net form partitioning body 106, are connected by means of the conventional joint 104 in order to form small scale pipe structures, such as a recovery plate form, a jumble kart, a screen or so forth as shown in FIG. 38, it becomes necessary to cut away the fitting ribs 107 at the end portions of the resin-coated steel pipes 108 to be engaged with the cylindrical tubes 101 and 102 of the joint 103.
Therefore, it requires a work load for a fabrication process which inherently result in increasing cost.
On the other hand, upon assembling of a pipe framework, a drawback is encountered in that a corner portion of the edge of the partitioning body 106 is externally exposed associating with cutting away of the fitting rib 107 at the end portions of the resin-coated steel pipes 108 on the side of a reentrant angle of the adjacent two cylindrical tubes 101 and 102 of the joint 103, as shown in FIG. 39.
In order to avoid such drawback, it may be possible to provide a fabrication process for the joint 103 in order to form axially extending partial slits 109 and 110 on the side of the reentrant angle of the adjacent two cylindrical tubes 101 and 102 of the joints 103 for permitting the pair of fitting ribs 107 of the resin-coated steel pipes 108 to project therethrough, as shown in FIG. 40.
However, similar to the foregoing prior art, such measure requires extra workload for the fabrication process which inherently results in increasing cost.
In addition, by formation of the slits 109 and 110, a bending strength of the joint 103 can be significantly lowered. This drawback is equally encountered even when the slits 109 and 110 are formed initially before molding process of the joint 103.
Furthermore, upon assembling the pipe framework, similar to the foregoing prior art, a drawback that the corner portion of the edge of the partitioning body 106 is exposed to cause degradation of external appearance on the side of the reentrant angle of the adjacent two cylindrical tubes 101 and 102 of the joint 103, as shown in FIG. 41.
In FIGS. 40 and 41, the reference numeral 111 denotes a synthetic resin inner cap fitted over the end portion of the resin-coated steel pipe 108.
On the other hand, in order to avoid the drawback of the prior art, it is possible to form a slit 115 over the entire length in a molding process or the fabrication process so that the slit 115 is located within one plane including respective axes for permitting the fitting rib 107 of the resin-coated steel pipe 108 to project therethrough, on the reentrant angle side of adjacent two cylindrical tubes 113 and 114, as in a joint 112 shown in FIG. 42.
However, when the pipe framework is assembled by abutting the resin-coated steel pipe 108 to be inserted into one cylindrical tube 113 with the other resin-coated steel pipe 108 to be inserted into the other cylindrical tube 114, and by fitting the inner cap 111 on the end portion of the resin-coated steel pipe 108 inserted into one cylindrical tube 113, in addition to the drawbacks similar to those encountered in the case where the partial slits 109 and 110 are formed, a drawback in exposure of the edge at the corner portion of the partitioning body 106 due to thickness of flange of the inner cap 111 on the side of the reentrant angle side of the adjacent two cylindrical tubes 113 and 114 of the joint 112, is encountered.